I'm a geochemist. In the past ten years I've fixed mass spectrometers, blasted sapphires with a laser beam, explored for uranium in a nature reserve, and measured growth patterns in fish ears, and helped design the next generation of the world's most advanced ion probe. My main interest is in-situ mass spectrometry, but I have a soft spot in my heart for thermodynamics, drillers, and cosmochemistry.

Tuesday, October 31, 2006

I realize that Canberra can be an intimidating city for people who grew up in non-synthetic communities. Despite the size, it is a quiet place. Down town is often dead quiet shortly after dark. The dispersed design of the city can discourage socializing, especially during the cold months of winter. And many people keep to themselves, their families, or their close networks of friends. However, none of this is an excuse for antisocial behavior.

Will the person who nicked the jars of Vaseline from the polishing lab please knock it off? I too have been single in Canberra, so I appreciate your situation. But trying to prepare an epoxy mount only to spend the afternoon searching the lab and heading down to storage is a pain in the butt. Used for its proper laboratory purpose, each one of those jars should last about 4 years. So you’ve swiped over a decade’s worth this month.

No, I’m not asking for you to return these things. Feel free to celebrate with your ill-gotten gain. But please don’t pilfer any more.

Saturday, October 28, 2006

I opened my door today to find a gleaming metal hand lying in the middle of the doormat. At first I thought it must have been severed from the arm of a robot. I don’t know many robots, but I suppose that this particular one could have been a light-fingered android from an automatonic society that practices Sharia law. Why it had been caught and punished on my front door was beyond me, but you can never be too sure these days.

So I picked up the hand, to get a closer view. Were the fingers electronic or hydraulic? Was it controlled by fiber-optic or wires? A brief inspection showed that it was in fact a shell. It was hollow on the inside, like a mitten or a glove. This was not a robotic hand at all. It was actually a glove made of steel. A gauntlet. And I had picked it up.

The trouble with picking up a gauntlet, even accidentally, is that once you have one in your hands, you can’t really put it back down again. It just isn’t done. So I had no choice but to determine what the challenge associated with the gauntlet might be. And the challenge is this.

Now, your ordinary man on the street might rightly think that writing a novel in 30 days is a crazy idea. But for me it is more than that. You see, I’m dyslexic. And not just a little bit dyslexic, either. I am absolutely completely fucking hopeless dyslexic. When driving, I don’t allow people to give me right or left directions, because it creates a traffic hazard the 50% of the time I turn the wrong way. It took me four goes and five years to pass my Australian car driving test as a result (the motorcycle test, which has no verbal instructions, was a cakewalk, even in a 4 degree mid-winter downpour).

Needless to say, writing my PhD thesis was a bit traumatic. It was worse than getting knocked off my motorcycle by a speeding Subaru. It was worse than getting interrogated on the Guyana/Brazil border by Polícia Federal who thought I was smuggling drugs (silly cops- geologists smuggle diamonds and gold, not drugs). But I’m getting a little bit tired of being afraid of words.

The best way to conquer a fear is to confront it. That’s one of the reasons I started this blog. It made me try to write complete paragraphs that were not spastic incoherencies. But I think I’ve gotten to the point where dipping a toe in the lake three times a week isn’t doing much for me anymore. I need to sink or swim.

If you’re scared of heights, jump out of an airplane without a parachute. If you’re scared of water, paddle a kayak over Niagra falls. If you’re scared of complete sentences, write a novel. In thirty days. If anyone wants to scrape me off the rocks at the end of the month, there’s a spatula in the kitchen.

Thursday, October 26, 2006

Life in the lab is just humming along this month. I think I’ve finally licked the alkali problem, but we won’t get to test until sometime next month. Ultra low-level alkali measurements just don’t interest that many people.

I’ve also been spending time running SHRIMP I, the original Sensitive, High-Resolution Ion Micro Probe. SI is a grand old machine, built before the era of modern computing. It is manually controlled. Instead of clicking on a flat screen, it uses dials and wheels and knobs for everything. Opening the sample lock requires spinning a huge valve crank with both hands, reminiscent of diving in a U-boat, or operating a 19th century steam engine.

One of the problems with the computer age is that computer interfaces are so anti-tactile. You just click stuff on screens. There is no texture, no clutching or smashing or tasting, like in the rest of geology. Visualization only goes so far in a science where grasping concepts and feeling out hypotheses is so important.

Of course, it would be unblog-like for me to simply complain about something in this medium without attempting a solution. So I will try to interface my computer with my rock hammer. A tap seems to have no effect, but if I take a hefty swing, then-

Tuesday, October 24, 2006

The incumbent was appointed to the senate seat vacated by billionaire John Corzine. Corzine left the Senate to become Governor, replacing democrat Richard Codey, who assumed the position after Governor Jim McGreevey resigned following a corruption scandal (giving his lover a government position despite not having the requisite qualifications). But the democrats’ predilection for avoiding elections whenever possible is not on the ballot this year; senator Menendez is.

And the senator has an appalling record on tax, free trade, and civil liberties. A typical partisan democrat, he seems to favor governmental intervention almost everywhere. And while he supports party-line democratic freedoms like abortion and gay rights, his record on universal freedoms, as opposed to interest group freedoms, is lacking. When push came to shove on votes that pitched basic democratic principles against populism, he caved, supporting the Military commission vote and the flag desecration amendment.

His opponent is the State Senator Thomas Kean Jr. I generally don’t like dynastic politicians (his Dad was the legendary NJ Governor and 9-11 commission chairman), but in his limited time in the state legislature, Kean Jr. has shown an ability to protect the environment, avoid partisanship, and fight corruption. I reckon he deserves a chance in the big leagues.

As an absentee voter, I will be voting this week. So here are my thoughts. But first, a caveat:

A while ago, the Bad Astronomer got criticized for posting some political thoughts on his blog. I have two words for such critics:

Bite me.

Participatory democracy (and really, is there any other kind?) is dependent on citizens communicating their thoughts in the leadup to an election. It is true that I am not a paid political pundit. But I am a voter, and thus it is my responsibility to look at the candidates, consider their strengths and weaknesses, and choose between them. If you have a problem with this, move to China. If you agree with the principle, but you think my choices are daft, feel free to comment. ‘tis the season.

The incumbent has sounded increasingly like a Democratic party hack as his time in Washington has increased. Still, before entering politics, he was a nuclear physicist. While I disagree with his occasional forays into identity politics and partisan sniping, I think that having a congressman who actually understands how nuclear weapons are built is an obvious asset to the nation these days.

The challenger is an Air Force veteran and small business owner. While there is nothing immediately discouraging about him, he doesn’t seem to grasp the subtlety of complex issues, and his anti-immigrant stance appears to border on the extreme.

Sunday, October 22, 2006

Western Geologist and Highly Allocthonous have already weighed in on this, but I figured I might want to float a highly speculative hypothesis. On Hawaii, most of the volcanism occurs on the southern half of the island, mainly from the Mona Loa and Kilauea volcanoes. Both of these volcanoes generally erupt from a series of NE/SW trending rifts- for the probable reason, see Western Geologists’ post on the regional stress field. If magma emplacement is causing substantial spreading in the southern part of the island, but not in the extinct north, then an accommodation transform fault may exist to allow that. Slip on such a fault would, as far as I can tell, be basically the right direction for the observed motion.

Hopefully the real seismologists will explain what actually happened at this week's GSA meeting. Is anyone going? Anyone? Bueller?

Wednesday, October 18, 2006

I heard back from Thomson Scientific last week. The good news is that an actual human being got back to me. The problem is that he doesn’t seem to understand what the issue I complained about was. He writes:

“This is how the author names are currently appearing on Web of Scienceand we processed them according to how the name would appear on thesource article. Let me know if I misunderstood.

Monday, October 16, 2006

Excuse the interruption, but have any of you other American expats out there had trouble or delays in getting abentee ballots? I usually get my in about 2 weeks, but it has been almost three so far. We have a nerw county commissioner, though, so maybe she just isn't up to speed yet.

I just wish that I didn't have to get up at 5:30 to call her office and inquire...

Saturday, October 14, 2006

At first glance, there is no obvious connection between zinc mining, neutron star formation, and nutty North Korean dictators. But a closer looks suggests that they may have something in common. And that something is the smallest object known to man.

The best way to determine whether or not the North Koreans actually detonated a nuclear weapon this week would be to detect a nuclear particle which is impossible to shield. One such particle is the neutrino. The problem with neutrinos that they are difficult to detect. But due to a stroke of luck, the Kamioka neutrino observatory, buried deep in an abandoned zinc mine in the Japanese Alps, just so happens to be located on the opposite side of the Sea of Japan as the North Korean test site.

If I was a qualitative blogger, I’d pat myself on the back for being so clever now, and go do something useful with my life. But since this is a science blog, I should at least try, in the roughest possible terms, to quantify this hypothesis. Is there any way to determine whether or not the Kamioka detector should be expected to pick up a nearby nuclear blast?

Addressing this problem could be tricky. On the one hand, I know jack-skittles about nuclear physics. On the other hand, I can look stuff up on the internet. So, taking the only two things I know about the Japanese neutrino detector, is it possible to estimate the sensitivity to a nuclear test.

First, the disclosure of those two things. I know that a recent paper used the neutrino detector to look at neutrinos produced by U and Th decay in the Earth’s interior. I also know that it detected the 1987 supernova in the Magellanic cloud.

Basically, this is a detection efficiency issue. If I can figure out the detection efficiency for a supernova, and then rescale that to the test, I can see how the number of expected neutrinos compares to the yield from the supernova.

The simplest test is this: to get a comparable number of counts, how much Pu do I need to fission?

Constant counts means that production/distance squared= constant for both the test and the supernova, assuming perfect transmission. If I can get the distances to both events, and the production for the supernova, then I should be able to calculate how much Pu I need to fission in North Korea.

So I need the following quantities-distance from Kamioka to test site. (there’s a national geographic atlas on my shelf)-distance from Kamioka to large Magellanic cloud (wikipedia)-number of neutrinos produced in a supernova.-number of neutrinos produced per unit mass of Pu fission.

I thought I would be able to simply look up the number of neutrinos in a supernova in wikipedia, but my searches of the obvious entries were fruitless. So if I want to know it, I will have to calculate it from first principles. Is that possible for an isotope chemist who knows squat about physics?

Well, wiki does tell me that the neutrinos are produced by the electron capture of protons in the Fe core of a giant star, as it transforms into a neutron star. How big a star? Rigel, in Orion, is given as an example of a blue supergiant. It is 20 solar masses. So if we simple assume that 20 solar masses of 56Fe transforms all of its protons into neutrons, the number of neutrinos produces is simply the starting number of protons. 20 solar masses of 56Fe worth of protons. A large, but tractable number.

The total number of nucleons in 20 solar masses is basically avagadro’s number times the mass in grams. In 56Fe, 46% of those are protons. So, using Wiki or google again, we have 6.0221415x1023 x 1.98x1030kg x 1000 g/kg x 20= ~2.4x1058 nucleons.

Holy leptons! I’ve never seen a number that big applied to physical science before. Astronomers are nuts. Of course, only 46% of them are protons- the rest are already neutrons, and thus don’t need to transform, but the total number of neutrinos emitted is still 1.1x1058.

Distance to supernova: 168,000 light years x 9.46x1012 km/lightyear = 1.59x1018 km. And I get to square it.

Distance to Kamioka from test site ~900 km.

Neutrinos generated at test site necessary to equal supernova flux in Kamioka: 7.68x1027

That’s big, but not outrageous. Avagadro’s number is working on our side now, so to get back to kilos (not grams) we can divide by 6.03x1026. In fact, we only need 5.8 kilos of nucleons to undergo beta decay in North Korea to produce an equivalent neutrino flux to the magellanic supernova. Depending on the bomb geometry, the total Pu needed for a bomb is in the 5-10 kg range.

So what fraction of Pu neutrons actually undergo beta decay? This is not a simple question to answer, but a rough estimate would suggest that it between 2 and 5%. For example, the net reaction 239Pu+n -> 90Zr + 147Sm + 3n requires eight beta decays. The neutrons will undergo beta decay in a vacuum, but in the real world, they are more likely to react with a nearby nucleus. The reaction product could either be stable or undergo further beta decay.

So in order to produce the neutrino flux equivalent to supernova 1987a, the North Koreans would have to fission between 110kg and 290 kg of Pu. This is about 2 orders of magnitude higher than what one would expect from a simple device, and 3 orders of magnitude larger than a dud.

Of course, the Kamiokande II detector used in 1987 has since been replaced by a bigger, better detector. And other factors, such as neutrino oscillation, neutrino energy, detection efficiencies between neutrinos and anti-neutrinos, and stuff I’ve never heard of have been ignored. But since the value is only a couple orders of magnitude short, it might be worth considering by someone less ignorant than I. So if I was a Japanese neutrino researcher, I’d lay down the line on the new nationalist PM. With a more sensitive detector, we might be able to call the North Koreans’ bluff.

Anyone with the tiniest smidgeon of knowledge in any of these subjects is welcome to tell me how wrong I am, and why.

Some arms control sites, such as this guy, have suggested that the test might be a dud or a fake, as so far no escaped radioactive material has been detected. Specifically, the issue of whether or not the test could have been faked tweaked my curiosity. Assuming a safe containment system, is there any way to tell whether a nuclear explosion actually occurred?

Obviously, the whole point of testing underground is to contain all the fission products and radiation generated by the blast. This generally works pretty well; the carbon 14 curve shows that after the cessation of atmospheric testing in the 60’s, the amount of anthropogenic 14C in the atmosphere began to decline sharply. So, if the alpha, beta, gamma, and neutrons from the test are all contained, is there anything else that might get out?

Thursday, October 12, 2006

There were rumors and press releases vibrating through cyberspace yesterday, suggesting that another test occurred, that it might have been an earthquake, and that nobody had any idea what was going on.

First, consider the location, shown on this map.The event was East of Japan, and relatively distant from North Korea. In addition, the depth was approximately 30 km, or about 3 times deeper than the deepest man-made hole ever drilled.

As is obvious from this figure, hundreds of similar quakes have occurred over the past 15 years. This earthquake is completely standard. The above link does show a great representation of the Japanese Benioff zone, however. As is shown by the color coding, the quakes in the downgoing slab increase in depth to the west. A rough schematic, using the same color coding as the USGS, is shown below.

Benioff zones are one of the classic indicators of plate tectonics, and thus are way more interesting than nuclear weapons.

Monday, October 09, 2006

The North Koreans claim to have tested a nuclear bomb at about 10:30 this morning (11:30am eastern Australia time). Can geology tell us anything about what actually happened? Let us see.

First stop, the comprehensive test ban treaty organization. In theory, they have a monitoring network designed to detect nuclear tests. Unfortunately, as a UN organization, their webpage is full of schemes and classifications and plans and protocols, and as of 6 this evening, there is no data, and no press announcement or other hint that anything happened.

So, what can we see? First, the depth of the earthquake is listed as 0 km. Most of the earthquakes in this region are very deep (see “historical seismicity” under the “maps” tag and look at the color scale). These deep quakes happen in the downgoing slab, as the old pacific plate subducts beneath Japan. Thus they are quite different than the zero depth M 4.2 event from this morning.

What else can we determine? In theory, an explosion should have an all-positive first motion tensor. Unfortunately, first motion tensors only seem to be calculated for quakes larger than M 5.0, so that test will need to wait until the North Koreans detonate a larger bomb. It might be possible to put a DIY tensor together by looking at the raw data, but I don’t know where that is archived.

Similarly, I seem to recall from my deep, dark past that explosions have a higher P/S wave ratio than normal quakes. But once again, this will require having the S wave data, and I don’t know where to find that, either. Hopefully some of the realseismologists who occasionally visit the lounge can give us some hints.

The only conclusion that I can draw is that there was a M4.2 event on land in North Korea with a zero depth, which was dissimilar to other seismicity in the area.

Sunday, October 08, 2006

Mrs. Lemming and I were required to spend some time in Sydney last week. It was a bit of a culture shock. Here in Canberra, the loudest morning noises are the warbles of the magpies and the screeches of the cockatoos. Last Friday we were woken at 5 in the morning by the sound of the pre-rush trucking. But this interminable traffic is merely an expression of Sydney geography.

In order to fully explain the geography of Sydney, a few simple mathematical concepts must first be explained. Geophysicists like to break the Earth down into simple hypothetical shapes, which they then integrate back together to approximate reality. One of the simplest of these shapes is the infinite half-plane. The infinite half-plane is a plane with a single linear edge, which stretches out to infinity in all other directions.

In urban planning, there is a form of development that closely approximates the infinite half-plane. I first observed this flying into San Jose, CA one night. Looking out the window of the aircraft, I could see the blackness of the Coast Ranges cutting north towards San Fran. East of that, the lights of Silicon Valley stretched out forever in every direction. What I observed was an infinite half-suburb.

Of course, the geography of Sydney is more complicated than a simple infinite half-suburb. The only Australian city that fits that category is Perth. But Sydney can be adequately described as two infinite half-suburbs, back-to-back, with a scenic harbour in between.

The harbour is finite, memorable, and spectacular. But on either side, an unending continuum of suburban sprawl stretches to the outer limits of mathematical comprehension. It is an unending tangle of six lane roads, traffic jams, and noisy, crowded tract housing.

A classical observer or remote sensing specialist might hypothesize that two infinite quarter suburbs might more accurately describe the Sydney geography, due to the presence of the Pacific Ocean to the East. But to do so would be a mistake. To consider the Pacific Ocean as a finite, tractable boundary is to ignore a fundamental truth of Sydney geography and culture. The Pacific Ocean is an asymptotic limit, which compresses space and roads in the coastal zone to ensure that, although the ocean can always be approached, it will always lie just out of reach.

The ocean is to Sydney what the speed of light is to relativistic physics. In physics, space and time dilate as c is approached, so that the energy required for the final acceleration reaches infinity. In Sydney, the dilation occurs in space and money as the ocean is approached, so that a flat becomes infinitely small, and the cost becomes infinitely high at the water’s edge. This creates an idealized fantasy. The beachfront apartment, like faster-than-light travel, becomes an impossible dream which can be perceived by anyone, even though a mathematical proof demonstrates that it cannot possibly exist.

Thus, although Sydney appears to have an eastern edge from a satellite, from the perspective of a motorist in the 'burbs, this spatial compression insures that you can navigate one-way streets and roundabouts forever while traveling east, and never hope to reach the sea. From the driver’s point of view, the streets are infinite and unending in every direction.

In a way, the utter despair inflicted by this geography was a motivating factor. When we lived in Sydney, Mrs. Lemming and I were constantly dreaming up schemes to escape. While waiting for my visa to be approved, I even created a wormhole, allowing me to bypass the space/fund continuum and reach the waves of Manly Beach using only a bicycle and seven Xeroxed pages of street directories.

Now that we live in Canberra, we are comfortable enough to happily potter away at home for weeks at a time. So in that sense, it is no surprise that Sydney is the state’s economic powerhouse. The poor souls who live there have no choice but to toil continuously, just to avoid the complete despondency that their forlorn surroundings would inflict, if they were foolish enough to lift their heads from their cubicles, get in a car, and drive through the never-ending traffic.

Thursday, October 05, 2006

So, in the first episode, I decided to investigate the dread option two. It really doesn’t make sense. This is science, how could anything possibly go wrong? The whole point of SHRIMP is to make U/Pb geochronology simple enough for a trained monkey to perform. So what could the problem be?

Well, in theory, the zircon could contain common Pb, in addition to the radiogenic Pb that was measured. So, what happens to the results when I apply a common Pb correction? The date of 15.2 Ga drops to 15.1 Ga. And the error increases from 0.3 to 0.4. Next?

What else could happen? Well, the first rule of analysis is this: always make sure that the thing you’re measuring is actually what you think it is. For Th, there is no question. But what about Pb?

Pb is a trickier matter. Zirconium and Hafnium are so similar in chemistry that it took science 99 years to isolate Hf from Zr and identify it as a separate element. As a result, Zircon contains substantial Hf- generally 1-2%. Because SIMS creates numerous molecular species, it is worth investigating the possibility of a molecular interference, such as 174Hf16O2 on 206Pb, or 176Hf16O2 on 208Pb.

As it turns out, the whole reason for building SHRIMP back in the 70’s was to have an ion probe with enough mass resolution to separate these peaks. Hf and O both have higher binding energies, and therefore lower mass/amu, than does Pb. Specifically, 206Pb has a mass defect of -27mAMU, while 16O is -5.1 and 174Hf is -59.9. So the HfO2 peak should be 43.1 mAMU lighter. This is seen in figure 1, a mass scan taken on SHRIMP 1.

A few caveats about these figures. First of all, these are quick-and-dirty, low resolution mass scans, so SHRIMP-haters should not use these peak shapes as evidence that the machine is inherently imprecise. Secondly, these are all scans of the Temora standard, correctly centered on Pb, and not of the pre-universal grain. Thirdly, I know that the calibration of the X axis is off. Setting this is generally more trouble than it’s worth, as we measure peak positions relative to each other; the nominal “absolute” value is not all that important.

Anyway, as fig 1 shows, The HfO2 and Pb peaks are clearly resolvable. Furthermore, in this grain, the 206Pb peak is considerably larger than the HfO2 peak. This is not the case for the mass 208 peaks, as fig 2 shows.

There are two reasons for this. First, 176Hf is 33 times more abundant than 174Hf. Second, although the Th/U ratio of this zircon is greater than 0.3, Th has a much longer half-life, so relative to 206Pb, not much 208Pb has been produced in the 418 million year lifetime of this particular grain.

Thus, if the instrument was accidentally measuring HfO2 peaks instead of Pb peaks, one would expect to find very large Th ages, accompanied by modest 238U ages. That is exactly what was observed with the “pre-universal” grain. Unfortunately, the measured Th/HfO2 ratio is not very geologically useful.

As for how this happens, it is quite simple. The machine can be told to autocenter peaks, to allow it to correct for magnet instability. However, this centering assumes that the 206Pb peak will be larger than the HfO2 peak (such as is the case in fig1). If you have a young, or low U zircon, then the HfO2 peak may be larger. In such instances, the instrument will pick the Hf peak instead of the Pb peak, and the lab lemming who foolishly left centering on will get geologically meaningless results.

Anally observant readers will notice a discrepancy between my figures and my explanation. I won’t say what this problem is, but I will tell you this: The answer, in a single word, is:YTTERBIUM!

Tuesday, October 03, 2006

Last month, I payed out a couple of scientific databases over their inability to deal with authors who change their names. After a reader suggested that I was unfairly picking on huge corporations by insulting them in a blog without giving right of reply, I emailed both Google scholar and Thompson scientific to see why their databases weren’t able to determine that an author who changes her surname is still the same person. I still haven’t heard anything from Thomson, but Google sent me this reply:

“Hello Chuck,

Thank you for your note. As you may have noticed, Google Scholar is inbeta, and we're currently working out some of the kinks. We appreciateyour bringing this to our attention, and we'll pass it on to ourengineering team. Thank you for your assistance in improving GoogleScholar.

Disclaimer:

All opinions, measurements, figures, and facts on this page are the personal opinions of Charles W. Magee, Jr, and do not represent the views of any of his employers: past, present, present-but-about-to-be-past, or future. None of the content herein has been subject to peer review, and should be treated with caution or derision. Any passing mention of OSHA code violations, criminal activities, unethical or unscientific behavior, or the clandestine Australian nuclear weapons program are fictions created to make rhetorical points, and do not represent the reality of my, or anyone else's, workplace. Do not attempt any scientific protocols described herein at home, with the exception of the chocolate chip cookie recipe. Do not apply the products of that protocol to individuals with heart disease, diabetes, high blood pressure or cholesterol, egg, wheat, dairy, or chocolate allergies. Do not view this blog continuously for more than 45 minutes without stretching and taking other precautions to prevent computer-related chronic injury.
email labhampster@gmail.com, but replace hampster with the arctic rodent after which this blog is named.